Of course I don't think it should be a crime, and I think the police should/could have shown lenience here especially given recent events (presuming we know the full story of course).
But criminal damage is a crime, plenty of other people have been prosecuted for stickering and flyposting, I fail to see why gender critical people should be exempt from laws that apply to everyone else.
Have there been any prosecutions for Brexit stickers, Remain stickers, Indy ref stickers, anti-vaccination stickers (those are everywhere), or generic My Name Is [graffiti tag name] stickers?
If these prosecutions are such a normal part of life, why do local clubs and DJs place highly traceable stickers with their names, addresses, and details of events?